In leaving out mom and dad and any mention of genitalia, Silverberg has tacitly left the door open for gay couples, parents who use fertility treatments, donor insemination, surrogates and adoption, as well as grandparents and other family members raising children

Silverberg’s quest to exclude no one means he omits much in the book – including any mention of sex.

The point, he says, is to get children asking questions but letting parents answering them with however much detail they see fit.

In the end, Silverberg knows his target audience are kids who want “big, pretty pictures,” not reams of progressively minded text